The Secret to Designing an Intuitive UX

The Secret to Designing an Intuitive UX

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Match the Mental Model to the Conceptual Model

Imagine that you’ve never seen an iPad, but I’ve just handed one to you and told you that you can read books on it. Before you turn on the iPad, before you use it, you have a model in your head of what reading a book on the iPad will be like. You have assumptions about what the book will look like on the screen, what things you will be able to do, and how you will do them—things like turning a page, or using a bookmark. You have a “mental model” of reading a book on the iPad, even if you’ve never done it before.

What that mental model in your head looks and acts like depends on a lot of things

If you’ve used an iPad before, your mental model of reading a book on an iPad will be different than that of someone who has never used one, or doesn’t even know what iPads are. If you’ve been using a Kindle for the past year, then your mental model will be different from someone who has never read a book electronically. And once you get the iPad and read a couple of books on it, whichever mental model you had in your head before will start to change and adjust to reflect your experience.

Mental models have been around for a long time

I’ve been talking about mental models (and their counterparts, conceptual models, which we’ll get to shortly) since the 1980s. I’ve been designing interfaces for software, websites, medical devices, and even microwave ovens for (way too many) years. I always enjoy the challenge of matching what is going on in the users’ brains with the constraints and opportunities of the technology of the day (or year, or decade). Interface environments come and go (e.g., the “green screen” of character based systems, or the blue screen of early graphical user interfaces), but people change more slowly. I find that some of the age-old user interface design concepts are still extremely relevant and important. Mental models and conceptual models are some of my favorite interface design concepts that I believe have passed the test of time.

Just how long?

The first person to talk about mental models was K.J.W. Craik in his 1943 book, The Nature of Explanation. Shortly thereafter, Craik died in a bicycle accident and the concept was dormant for many years, until the 1980s when the term reappeared. In the '80s, there were two books published with the title Mental Models:

A mental model represents a person’s thought process for how something works (i.e., a person’s understanding of the surrounding world). Mental models are based on incomplete facts, past experiences, and even intuitive perceptions. They help shape actions and behavior, influence what people pay attention to in complicated situations, and define how people approach and solve problems.

What is a mental model in interface design?

In the field of user interface design, a mental model refers to the representation of something—the real world, a device, software, etc.—that the user has in mind. It is a representation of an external reality. Users create mental models very quickly, often before they even use the software or device. Users’ mental models come from their prior experience with similar software or devices, assumptions they have, things they’ve heard others say, and also from their direct experience with the product or device. Mental models are subject to change. Users refer to mental models to predict what the system, software, or product is going to do, or what they should do with it. The best history and definition I’ve found about mental models as they relate to software and usability is a 1999 article by Davidson, Dove, and Weltz titled Mental Models and Usability.

What is a conceptual model?

In order to understand why mental models are so important to designing user interfaces, you have to also understand what a conceptual model is. A conceptual model is the actual model that is given to the user through the interface of the product. Going back to the iPad ebook example, you have a mental model about what reading a book will be like in the iPad, how it will work, what you can do with it. But when you sit down with the iPad, the “system” (the iPad) will display what the conceptual model of the book app actually is. There will be screens, and buttons, and things that happen. The actual interface is representing the conceptual model. Someone designed a user interface and that interface is communicating to you the conceptual model of the product.

Okay, so what?

At this point you might be asking, “So? Why do I care about this mental model/conceptual model idea?” Here’s why you should care: Everything we do in the field of user experience is, ultimately, about the match, or mismatch, between the users’ mental models and the product’s conceptual model. Here are some examples:

If the product’s conceptual model doesn’t match the user’s mental model, then the user will find the product hard to learn and use.

If the designers of the conceptual model didn’t take the user’s mental model into account then it is highly likely that the product will be hard to learn and use.

If there are multiple user groups (people who have used a Kindle before, people who have never read books electronically, etc.) and the conceptual model is designed to match just one mental model, then the other users will find the device hard to learn and use.

If the conceptual model was not really designed, but is just a reflection of the underlying hardware or software or database, then the conceptual model will not match the user’s mental model very well, and the users will find the device hard to learn and use.

Sometimes you know that the mental model of one or more user groups will not fit the conceptual model, and you want to change the user’s mental model so that it matches the conceptual model you have designed. For example, you know that people who have only read real, physical books will not have an accurate mental model of reading books on the iPad. You can use a short training video to change their mental model before the iPad even arrives at their door. In fact, the main purpose of training should be to adjust a user’s mental model to fit the conceptual model of the product.

Terminology is important

Usability specialists and interface designers don’t always agree on what to call something. So I have to warn you that the way I’m using the term mental model does not fit with at least one of the new definitions I’ve been reading and hearing about lately. Indi Young has written a book recently called Mental Models, and she’s using the term in a different way. She diagrams the behavior of a particular audience doing a series of tasks, including their goals and motivations. Then underneath that she describes what the “system” or product will do, or be like, in order to match the task. This entire structure she calls a “mental model.” I think her technique is an interesting one, but I do wish she had used a different term to describe her diagrammatic representations. Her methodology and its output look useful, but it doesn’t match the definition of mental models that’s been around for a long time.

It’s all about the mental and conceptual models

I hope you are starting to see that mental models and conceptual models are very powerful for the work that an interface designer does. I have sometimes gone so far as to say that almost everything we do during a user-centered design process has to do with either:

This is why I say that the secret to designing an intuitive user experience is making sure that the conceptual model of your product matches, as much as possible, the mental models of your users. If you get that right you will have created a positive and useful user experience.

I am failing to see the difference between this model and Indy Young's, In this day and age people tend to think about the conceptual model (the system, or content) in relation to what tasks they can complete (the mental model). An example: if I was to tell you there was a new application that allows you to find restaurants in your area , the more you check-in to a particular resturant you are awarded discounts or credits. You may think in terms of " yelp, foursquare, groupons, " but you may also think in terms such as "log in, search, get directions, check-in, credits ". Understanding that an older use case will not have this model, but in relation to a good majority that uses web applications, how is this not the same thing?

i read ur introduction only and i not really agree, i bet that most ppl will think in term of pdf since most of ppl read digital book in pdf on computer/mobile first. and i do sure that most ppl will feel fresh and impressive when they find out they can read book like flipping the page/bookmark in like physical book.

As the article mentions, sometimes you need to alter the mental model of the user to align it with your conceptual model (rather than the other way round), otherwise you'll end up with several identicle products that although familiar, are fundamentally inferior to the possible potential of the conceptual model. I suppose to some extent this should correlate with learnability etc.

The point is simply that mental models need to be considered when creating the coneptual model; the application of that consideration isn't black and white :)

I would like to second your assertion that terminology has an overall impact on the usability of your interface design. We have found, that even in interfaces that are not replications of a real life item (and therefore not assigned a mental model automatically) if we can find terminology that is representative of a mental model function - even if not a mental model that is logically associated with the interface - helps users understand and use our systems with less confusion. Overly-technical terminology, on the other hand leads to an increase in confusion and customer service calls.

Thanks for this historical review and contextual understanding. I think Indi Young's work is important but we have to agree on the fundamental vocabulary we use in order to use it and move the practice forward.

This is a great article. Don Norman wrote about Mental Model in his 2 books - Emotional Design and The Design of Everyday Things. I'm always interested in the part of 'matching' the user's mental model with the designer's conceptual model. Ideally both models should be identical. However there are not many literatures on the method to achieve this, and how to measure it, any benchmark? In my personal experience, there are other mental models, such as the client’s mental model and the decision maker’s mental model which involve in the whole design process as well, which I might to say ‘interfere’ the ‘matching’ process of user-designer models. Any comments?

Tom -- John and Mike are addressing the issue you raise -- Sometimes you know that you want to create a new conceptual model that is different from the users' mental model. You know that they will eventually have to adjust their mental model to fit the new product or software or conceptual model that you have created. You can do that, but you should be aware that you are doing that, and be aware that the users are going to have to make a shift. You will want to purposely design that conceptual model to be different from their current mental model. The point is to know that you are doing that, and to know that it means that your design may initially not be intuitive or highly usable at first. It might be worth the switch, but it will be a switch.

Brett -- Users always have a mental model in operation, but it may be very far off from what you have or what they hope you have. They may not be able to articulate it either. This is what our analysis is all about -- to understand what their mental model is, by interviewing, observing, prototyping, and getting feedback.... uh oh, I can feel another blog post forming!

Mike -- your point about making abstract concepts tangible... "through the language and interaction patterns we create" -- the language and interaction patterns are the conceptual model that you build, and yes, the new conceptual model will help the user adjust to a new mental model. And yes, you need prototyping and iterative design to get this right.

Indy Young's book starts out with another "secret" to user-centered design: the non-directed interview. The iPad example is accessible to most casual readers of this article. However, much of software interaction design expresses abstract concepts that we must make tangible at a cognitive level; concepts that were previously foreign and intangible. In many cases, we are helping users of software systems to create their own mental models through the language and interaction patterns we create, appropriate to the the user's context. This is very difficult to do without prototyping and usability studies and iterative design.

Great article. Thanks for raising the awareness of this awesome concept!

This is a great read. Very interesting ideas here. One issue I know that hinders me from exploring the clients mental modal is they often don't have one or they assume that my way is the best way. What would you suggest are some good ways to figure out your clients and their users potential mental models?

Great post! One of the things that fascinates me about this whole topic is, that after you actually read about it, it all seems so self-evident, which makes it an easy to understand yet powerful tool to improve user experience!

This concept of a mental model was there earlier too. I refer to the story of the 4 blind men and an elephant, and how each one describes one limb of the elephant by touch and feel, but the resulting picture it does not add up to an elephant. Most UI interfaces are like that i think..

As a rookie tech writer, i remember the aha moment when the understanding of the system happened, and it no way reflected what i had understood and written till then.

Very often, the ui is planned last and in a shoddy manner. but of course, Steve Jobs has redefined the way design looks like and work like. I LIKE this new wave..

So having files into folders (good so far) into windows onto desktops dicreases the learning curve?

Doesn't this also work backwards : drawing from a common mental model creates expectations that may not be met by the concept model of the task at hand or is this just a matter of the concept model design quality?

ok I get that

Neither data nor frame comes first; data evoke frames and frames select and connect data. When there is no adequate fit, the data may be reconsidered or an existing frame may be revised.

http://en.wikipedia.org/wiki/Sensemaking

The way I see it the role of the concept model is not to match a mental model but to foster sensemaking which in turn will provide a mental model for the task at hand on which flow will depend. This way it is not a matter of matching the variety of mental models people might have or the lack of them.

nice article but I can't agree with everything. Example: I don't have iPad or iPhone. I have my LG Arena and I like printed books. Sometimes, I read some e-book on my computer, but if I never use computer and never seen iPad in picture, my mental model will be different. And if developers of iPad (or iPhone) made their products by my mental model, they would never sell their products (my metal model would be poor).

I know - my English is poor (and I am sorry), but I just want to say, that we don't have to make products (our design) by metal model of our users, but we should make products much better (more simple and better looking) than mental model of our users.

What you both describe sound a lot like the methodologies and activities that I taught for many years. In my user centered design seminars I taught my own UCD methodology called InterPhase 5 or I5 for short. In that there were activities of describing the users' current tasks and how they did them, then describing the task analysis that would take place in the future when the new system was in place... then doing a noun and verb analysis of those scenarios (stories), and from that constructing an "object/view" table and from there designing object and action interactions... etc etc...(A special mention to Dean Barker who helped me put it all together). Human Factors International (where I work now), has a version of the object/action/view idea that is called "primary noun analysis".

Very cool article. I hope you will make a book out of these ideas! I often use modelling techniques to think about/model
- tasks and activities (verbs, like described in indy's book http://bit.ly/9LQLKo)
- objects and things (nouns, like described here http://bit.ly/bBzYsy)
- systems (relationships and flows)

If used all together, this can lead to a very detailed representation of a conceptual model that can be verified against mental models of users via card sorting or even just looking at the models together and discussing.

Each task then becomes a potential candidate for a button or link, and each object could be a row in a table, a graphic etc - the systemic model captures what belongs together on one screen or in one workflow.

The challenge is to capture this data from real research and validation, to transition this into design decisions, and to convince clients to invest in this kind of work!

I'm currently using jeff pattons user story mapping to help project teams collaborate based on a users mental model. So far its been both great for focussins teams and visualising the conceptual model in its early stages. Great way to get business talking in terms of the user. About to roll out the technique across the business...suits agile types well with the familiar card layout